Nu-phenyl-nu&#39;-sec-alkyl-ortho-phenylenediamines



Unite tates atent O 3,290,376 N-PHENYL-N-SEC-ALKYL-RTHO- PHENYLENEDIAMINES Joseph A. Chenicek, Long Grove, and Wiiiiam K. T.

Gieim, llsiand Lake, Iii assignors to Universal Oil Products Qompany, Des Piaines, lit, a corporation of Delaware No Drawing. Fiied Dec. 21, 1964, Ser. No. 420,137 4 Claims. (Cl. 260-576) This is a continuation-in-part of our copending application Serial No. 145,980 filed October 18, 1961, now abandoned, and relates to a novel composition of matter.

The novel composition of matter is a derivative of ortho-phenylenediamine in which a phenyl group is attached to one nitrogen atom and a secondary alkyl group of from 3 to 12 carbon atoms is attached to the other nitrogen atom. It is essential and critical that each of the nitrogen atoms must be substituted in the manner herein set forth. As will be hereinafter shown in detail, these novel compounds possess unexpected superior properties, which important advantages are not obtained when other substituents are attached to the nitrogen atoms.

In one embodiment the present invention relates to N phenyl N sec alkyl ortho phenylenediamine in which the alkyl contains from 3 to 12 carbon atoms.

In another embodiment the present invention relates to N phenyl N sec butyl ortho phenylenediamine.

A preferred compound of the present invention is N- phenyl N sec butyl ortho phenylenediamine. Other compounds of the present invention are N-phenyl-N-is o-propyl-ortho-phenylenediamine, N-phenyl-N-sec-amyl-ortho-phenylenediamine, N-phenyl-N-sec-hexyl ortho-phenylenediamine, N-phenyl-N-sec-heptyl-ortho-phenylenediamine, N-phenyl-N-sec-octyl-ortho-phenylenediamine, N-phenyl-N-sec-nonyl-ortho-p henylene diamine, N-phenyl-N-sec-decyl-orthophenylenediamine, N-phenyl-N-sec-un decyl-ortho-phenylenediainine, Nphenyl-N sec-do decyl-ortho-phenylenediamine, etc.

As hereinbefore set forth, it is essential that one nitrogen atom be substituted by a phenyl group and that the other nitrogen atom be substituted by a secondary alkyl group. As will be shown by the data in the appended examples, it surprisingly has been found that the orthophenylenediamine derivatives having this particular configuration possess superior inhibitor properties as cornpared to the corresponding para-phenylenediarnine derivatives in certain gasolines.

This surprising discovery is very specific and does not prevail with other phenylenediarnine derivatives. For example, when both nitrogen atoms are substituted by secondary alkyl groups, the ortho-phenylenediamine derivatives are of lower potency than the corresponding para phenylenediamine derivatives. This peculiar phenomenon also does not apply when only one nitrogen atom is substituted by a phenyl group because here again the orthophenylenediamine derivative is inferior to the para-phenylenediamine derivative. In addition, the pecular phenomenon does not occur in the case Where one of the nitrogen atoms is substituted by benzyl instead of phenyl.

From the above discussion, it will be noted that the surprising advantages of the novel compounds of the ice present invention are very specific and prevail only in the case of the limited substitutions hereinbefore set forth. Furthermore, this discovery is most surprising in view of the extensive investigation of phenylenediamine compounds by many investigators in the past and no one has heretofore're'ported any ortho-phenylenediamine derivatives to be even equal, let alone superior, to the para phenylenediamine derivatives for use as inhibitors in organic substrates. This is confirmed by the fact that, while many para-phenylenediamine derivatives are being used commerically at the present time as inhibitors to gasoline, no ortho-phenylenediamine derivative is marketed by others for use as an inhibitor in gasoline.

The N phenyl N sec alkyl ortho phenylenedianiines of the present invention are prepared in any suitable manner. In a preferred method, ortho-nitro-diphenylamine is reductively alkylated with a suitable ketone to obtain the desired N-phenyl-N-sec-alkyl-orthophenylenediamine. Thus, N-phenyl-N-isopropyl-orthophenylenediamine is prepared by the reductive alkylation of ortho-nitro-diphenylamine with acetone. Similarly, N- phenyl N sec butyl ortho phenylenediamine is prepared by the reductive alkylation of ortho-nitro-diphenylamine with methyl ethyl ketone. Likewise, N- phenyl N sec octyl ortho phenylenediamine is prepared by the reductive alkylation of ortho-nitro-diphenylamine with methyl hexyl ketone. Other compounds are prepared by substantially the same method of manufacture or by any other suitable method.

The reductive alkylation is effected in any suitable manner. A suitable catalyst for effecting the reductive alkylation reaction comprises an intimate mixture of copper oxide, chromium oxide and barium oxide. Other catalysts include nickel, nickel-kieselguhr, nickel sulfide, copper sulfide, molybdenum sulfide and those containing platinum, palladium, etc. The temperature to be employed generally will depend upon the particular catalyst being used. When employing the mixture of copper oxide, chromium oxide and barium oxide catalyst, the tempera ture is Within the range of from about 200 to about 500 F. The hydrogen pressure employed is within the range of from about to 3000 pounds or more of hydrogen and preferably within the range of from about to about 1500 pounds.

As hereinbefore set forth, the novel compounds of the present invention are of surprisingly high potency as inhibitors to gasoline. The gasoline may be straight run gasoline, thermally cracked gasoline, catalytically cracked gasoline, thermally reformed gasoline, catalytically reformed gasoline, coker distillate gasoline, or mixtures thereof. In many cases the gasoline presently being marketed comprises a blend of different gasolines, which blend includes one or more of the gasolines hereinbefore set forth, as well as alkylate, isomerized paraffins, etc. In addition, most gasolines contain tetraethyl lead in order to further improve the octane number of the gasoline. Also, present practice is to include other additives in gasoline as, for example, deicer, metal deactivator, detergents, etc. Accordingly, a satisfactory inhibitor for use in such blended gasolines must be readily soluble in the gasoline and also must be compatible with the other additives incorporated in the gasoline. Furthermore, it is of impor' tant advantage when the inhibitor also possesses inhibitor sweetening properties. This means that the inhibitor will serve to catalyze the oxidation of trace mercaptans in the gasoline in order to convert the sour gasoline into one that is sweet.

The N-phenyl-N'-sec-alkyl-ortho-phenylenediamine is used in a stabilizing concentration in the gasoline. In general, this concentration is within the range of from about 0.0001% to about 1% and more particularly from about 0.001% to about 0.01% by weight of the gasoline. As hereinbefore set forth, it is understood that the inhibitor may be used in conjunction with other additives which are to be incorporated in the gasoline as, for example, tetraethyl lead, metal deactivators, dyes, deicers, detergents, etc. When desired, the inhibitor may be formed as a solution in a suitable solvent which may comprise gasoline, selected aromatic fraction as benzene, toluene,

Example III As hereinbefore set forth, it surprisingly has been found that the N-phenyl-N-se-c-alkyl-ortho-phenylenediamines were of greater potency than the corresponding N-phenyl N'-sec-alkyl-para-phenylenediamines. These results are reported in the following table in which the different inhibitor-s were evaluated in a catalytically cracked gasoline having a blank induction period of 165 minutes.

xylene, cumene or mixtures thereof, or selected paraffin fraction such as hexane, heptane, nonane, octane, etc., or mixtures thereof.

The following examples are introduced to illustrate further the novelty and utility of the present invention but not with the intention of unduly limiting the same.

Example I N-phenyl-N-sec-butyl-ortho-phenylenediamine was pre- "pared by reductive alkylation of ortho-nitro-diphenylamine with methyl ethyl ketone at an inlet temperature of 270 F. and a hydrogen pressure of 1000 pounds per square inch in the presence of a platinum-alumina catalyst containing about 0.5% by weight of platinum. The methyl ethyl ketone is used in a mol ratio to ortho-nitrodiphenylamine of about 16:1. The reactants are passed downwardly through a fixed bed of the catalyst disposed in a reactor and the efiluent products are withdrawn from rivatives.

From the data in the above table, it will be seen that orth-o-phenylenediamine derivatives were considerably superior to the corresponding para-phenylenediamine de- As hereinbefore set forth, this is surprising because, according to the teachings of the prior art, only the para-phenylenediamine derivatives were of sufficient potency to be acceptable for commercial use.

Example IV As hereinbefore set forth, the improved benefits of the present invention are very specific and critical in the nature of the substituents. It is essential that one of the nitrogen atoms is substituted by a phenyl group and the other nitrogen atom is substituted by a sec-alkyl group. This is illustrated in the following table in which various ortho-phenylenediamine derivatives are compared with para-phenylenediamine derivatives. The runs reported in Table II were made in other samples of the the reactor and separated by fractionation. Excess hysame gasoline described in Example III.

TABLE II Run No. Additive Concentration, Induction Percent Period 1 None 165 8 N,N'-di-see-0etyl-ortho-pheuylenedi- 0.002 450 amine.

drogen is recycled for further use in the reactor, and the liquid products are fractionated to recover N-phenyl-N'- sec-butyl ortho phenylenediamine.

The N-phenyl-N-sec-butyl-ortho-phenylenediamine is recovered as a viscous liquid, having a molecular Weight of 240, a density of about 1.040 g./ml., and a boiling point of about 650 F.

Example II N-phenyl-N-isopropyl-ortho-phenylenediamine was prepared in substantially the same manner as described in From the data in the above table, it will be seen that the para-phenylenediamine derivatives were superior to the corresponding ortho-phenylenediamine derivatives. In runs 8-11, both nitrogen atoms were substituted by sec-alkyl groups. In runs 12-15, only one nitrogen atom 7 was substituted by a phenyl group. This further demonstrates the specific and critical requirements of the novel compounds of the present invention in order to obtain improved results with the ortho-phenylenediamine derivatives as compared to the para-phenylenediamine Example 1 except that acetone was used as the ketone. derivatives.

Example V The essential requirements that one of the nitrogen atoms be substituted by a phenyl group and that the case. These results were obtained in a thermally cracked gasoline which is ditficult to stabilize and which had a blank induction period of 75 minutes.

TABLE IV Run No. Additive Concentration, Induction Percent Period None N-phenyl-N-scc-buty1-ortho-phenylcnedi- 0. 002 175 amino.

do 0.004 270 N,N-di-sec-butyI-orthophenlenediamiue 0. 002 105 do O. 004 150 other nitrogen atom be substituted by a sec-alkyl group is further demonstrated by the data reported in the following table. These results were obtained in a thermally cracked gasoline which had an uninhibited induction period of only 70 minutes and is difficult to From the comparison of runs 24 and 25 with runs 26 and 27, it will be seen that the compounds of the present invention were slightly less than twice as potent as compared to the compounds containing two sec-alkyl substitutions. This again demonstrates the criticality and selectivity of the novel compounds of the present From the data in the above table, it will be seen that even in this gasoline which is difiicult to stabilize, the novel compound of the present invention was effective in stabilizing the gasoline. In contrast, when a benzyl substituent was present instead of the phenyl substituent on one of the nitrogen atoms, the additive was of substantially no potency. As mentioned above, this further illustrates the specificity of the novel compound of the present invention.

Example Vl In still another demonstration of the specificity of the novel compounds of the present invention, the following table reports results obtained in a comparison of compounds in which one of the nitrogen atoms is substituted by a secondary butyl group in both cases and the other nitrogen atom is substituted by a phenyl group in one case and by another secondary butyl group in the other We claim as our invention:

1. N phenylN-sec-alkyl-ortho-phenylenedianiine in which said alkyl contains from 3 to 12 carbon atoms.

2. N-phenyl-N-isopropyl-ortho-phenylenediamine.

3. N-phenyl-N-sec-butyl-ortho-phenylenediamine.

4. N-phenyl-N-sec-octyl-orthophenylenediarnine.

References Cited by the Examiner UNITED STATES PATENTS 2,038,631 4/1936 Bennett et al. 44-74 2,451,642 10/1948 Watson 25250 2,734,808 2/1956 Biswell 260576 X 3,035,014 5/1962 Popolf et a1 260-576 X CHARLES B. PARKER, Primary Examiner.

DALE R. MAHANAND, Assistant Examiner. 

1. N-PHENYL-N''-SEC-ALKYL-ORTHO-PHENYLENEDIAMINE IN WHICH SAID ALKYL CONTAINS FROM 3 TO 12 CARBON ATOMS. 